Automatic circuit breaker



March 27, 1934. J. sAcHs AUTOMATIC CIRCUIT BREAKER Filed Jan. 15, 1931 4 Sheets-Sheet 1 771'5222021 Jaagph 55/75. 1/. W

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March 27, 1934. J. SACHS AUTOMATIC CIRCUIT BREAKER Filed Jan. 15, 1931 4 Sheets-Sheet 2 March 27, 1934. J. sAcHs AUTOMATIC CIRCUIT BREAKER 4 Sheets-Sheet 3 Filed Jan. 15, 1931 fizz/52715 L72.

March 27, 1934. s c s 1,952,632

AUTOMATIC CIRCUIT BREAKER Filed Jan. 15, 1931 4 Sheets-Sheet 4 Jm EF/b 0/. J0 550. Each 5.

Patented Mar. 27, E934 UN TED STATES ICE 20 Glaims.

The present invention is particularly applicable to automatic circuit breakers of the type dis closed in my patents for automatic circuit breakers, No. 1,812,842 and No. 1,811,970, both dated June 30, 1931. I

The general object of the invention is to provide for a circuit breaker of the type referred to, an operating means whichserves to move the contact member with a snap action so as to provide a quick break, and preferably also a quick make.

A more specific object of the invention is to provide certain advantageous and simple me-= chanical details by virtue of which the beforementioned general object is attained.

Another object of the invention is to provide a circuit breaker havingspecial provision for the extinguishment of any arcs that may be formed.

Still further objects of the invention will be apparent from the following specification and claims.

in the accompanying drawings I have shown two embodiments of the invention, but it will be understood that the drawings are intended for illustrative purposes only and are not to be construed as defining or limiting the scope of the invention, the claims forming a part of this specification being relied upon for that purpose.

Of the drawings:

Fig. l is a front view of a circuit breaker ern= bodying the invention, the circuit breaker comprising two mechanisms for breaking the two legs of a circuit. In this view the main cover of the enclosing cabinet is omitted, as is also the cover for the left hand mechanism. The cover for the right hand mechanism and also some of the parts of the said unit are shown in section along the line 1-1 of Fig. 3.

Fig. 2 is a .top view of the circuit breaker shown in Fig. 1, the main cabinet and the cover for the left hand mechanism being shown in transverse section.

Fig. 3 is a vertical sectional View taken along the line 3-3 of Fig. 1, the enclosing cabinet be ing omitted.

Figs. 4. and 5 are fragmentary views similar to Fig. 3 but showing the parts of the circuit breaker mechanism in diiferent relative positions.

Fig. 6 is a fragmentary vertical sectional view taken along the line 6--6 of Fig. 1.

Fig. 7 is a view similar to Fig. 6 but showing the parts in difierent relative positions.

Fig.3 is a perspective view of one of the arc rupturing elements.

(Cl. 200l16) Fig. 9 is a side view of a somewhat different circuit breaker embodying the invention.

Fig. 10 is a vertical sectional view taken along the brokenline 10-10 of Fig. 9.

Figs. 11 and 12 are fragmentaryviews similar to Fig. 10 but showing the movable parts in different relative positions.

Fig. 13 is a plan view with a part of the casing omitted, and showing the interior parts of the circuit breaker mechanism in the relative posi tions which they occupy in Fig. 10.

Fig. 14 is a detail perspective view showing the more important parts of the circuit breaker mechanism as illustrated in Figs. 9 to 13, these parts being separated from each other in order that the details of construction may be more clearly understood. The parts are in relative positions corresponding approximately to those shown in Figs. 10 and 13. I

The circuit breaker as shown in Figs. 1 to 8 will be first described. This circuit breaker has two separate mechanisms adapted to be included in different legs of a circuit and arranged for normal operation by a single operating means or handle, or for automatic operation independently of each other. As concerns some of the features of the invention it is immaterial whether a plurality of circuit breaker mechanisms be pro= vided or only one; but as concerns other features of the invention, the provision of two circuit breaker mechanisms under the control of a single operating means is important.

As shown in Figs. 1 and 2 there is provided a main insulating base 1, on which all of the parts of the circuit breaker are mounted. Carried by the base 1 at each side thereof are two stationary electric contacts 2 and 3, these being spaced apart transversely and adapted to be engaged by movab1e.;contacts of the corresponding circuit breaker mechanism to be presently described. Each 'of the contacts 2 and 3 comprises a flat strip of metal bent as shown most clearly in Figs. 3, a and 5, and having the contact face thereof located in a transverse plane. Each contact 2 is electrically connected by means of a strap 4 with a wire terminal 5 and each contact 3 is electrically connected by means of a strap .6 with a wire terminal 7. 1

All of the movable parts of the circuit breaker are carried by a central metallic bracket 8 which is secured tothe insulating base 1. As illustrated, the bracket 8 comprises two parallel metallic plates 9,9 provided with mounting flanges 9 and 9 which are engaged by screws 10, 10 extending forward through the base 1. Near the Sil its

front the two plates 9, 9 are offset toward each other and are connected by a shouldered rivet l1.

Bearing bushings 12, 12 are carried by the respective side plates 9, 9. Rotatably mounted in the said bearing bushings 12, 12 is a shaft 13 having a crank portion 15 which is positioned between the said plates 9, 9. The cranked shaft 13 is adapted to oscillate, the extent of oscillation being limited by means of studs 14, 14 which are riveted in place at the inner sides of the plates 9, 9. I

The shaft 13 serves as the means for supporting and moving the two electro-responsive circuit controlling mechanisms, these mechanisms being carried on the shaft at opposite sides of the central supporting bracket 8. One of the circuit controlling mechanisms will now be described, it being understood that the two mechanisms are or may be identical in construction. Rotatably mounted on the shaft 13 is a contact member which includes two spaced side plates 15, 15. The two plates are held in spaced relationship in part by a spacing bar 16 and in part by other means to be presently described. The inner plate of the contact member abuts against the corresponding bearing bushing 12 and the outer plate is engaged by a cotter pin 17 which prevents endwise movement of the contact member with respect to the shaft 13.

Two laterally projecting movable contacts 13 and 19 are carried by the contact member at the sides thereof, these contacts projecting laterally from the respective side plates 15, 15 and being adapted to be engaged with and disengaged from the respective stationary contacts 2 and 3 which have already been described. The said contacts 18 and 19 are in the form of metallic plates which project inward through slots in the respective side plates. Extending transversely between the two side plates is an insulating bar' 20, the ends of which also project into the slots in the side plates as clearly shown in Figs. 3, 4 and 5. The inner ends of the contacts 18 and 19 engage the bar 20 at the rear face thereof and are held in place by means of screws 21, 21. The bar 20 serves as an additional means for holding the plates 15, 15 in their proper spaced relation.

The contact member is biased for movement in the circuit opening direction, that is, in the counterclockwise direction, by means of a spring 22 surrounding the corresponding bearing bushing 12. One end of the spring engages the inner side plate of the contact member and the other end of the spring engages the adjacent side their outer ends is a small roller 26.

' Provision is made for releasably mechanically connecting the actuator 23 with the contact membr so that the actuator may serve its before-de- '-scribed purpose of moving the contact member for-normal switching purposes or to effect closing of the circuit after automatic opening thereof. An electro-resp'onsive means is provided which serves upon the attainment of abnormal The actuator also aesaeec current conditions in the circuit to release the said mechanical connection and permit the contact member to move independently of the actuator to its open-circuit position. Preferably and in accordance with the inventions set forth in the before-mentioned applications, at least one element of the electro-responsive means constitutes a part of the releasable mechanical connection between the actuator and the contact member. The said element is so constructed and so related to other parts that it is inherently responsive to abnormal current conditions in the circuit, ordinarily excess current; and by reason of an electro-responsive effect acting directly thereon, the said element is movable relatively to the member which supports it. This relative electroresponsive movement serves to render ineffective the said mechanical connection and thereupon the contact member is permitted to automatically move in the circuit opening direction independently of the actuating member.

I do not limit myself to an electro-responsive means of any one type, but I prefer an electroresponsive means of the type wherein the electroresponsive action is a thermal one. I have shown as the electro-responsive means a bi-metallic thermal element or strip 2'7. The strip 27 is substantially U-shaped and has the legs of the U connected respectively with the movable contacts 18 and 19. As illustrated there are connecting elements 28, 28 engaging the respective contacts and held in place by the screws 21, 21, and the end portions of the legs of the strip 27 are riveted to these connecting elements. It will be observed that the strip 27 provides an electrical connection between the two movable contacts 13 and 19, thus completing the circuit through the entire mechanism when the movable contacts 18 and 19 are in engagement with the stationary contacts 2 and 3.

The strip 2'7 is so shapedand so positioned that it serves in and of itself as a latch to hold the contact member and the actuator in normally fixed relationship with each other. For this purpose the strip 27 is prov ded with a pin 29 adapted to engage the roller 26. Under normal conditions the strip 2'? serves to mechanically connect the contact member and the actuator, but when the bi-metallic strip is heated by reason of the passage of excess current therethrough it is defiected upward so as to cause the pin 29 to disengage the roller 26. This permits the contact member to move automatically in the counterclockwise direction so as to separate the contacts 18 and 19 from the contacts 2 and 3 and thus break the circuit in two places.

When there are two contact members and two sets of stationary and movable contacts, it will be apparent that both contact members may be moved for normal switching purposes when the shaft 13 is moved, and it will further be apparent that either contact .member may move independently of the other to effect the opening of its own leg of the circuit upon the passage of excess current therethrough. For the sake of convenience the shaft 13 and the two actuators 23, 23 thereon will be referred to collectively as the actuating member.

For operating the actuating member there is provided a manually movable operating member, and this operating member is connected with the actuating member by a mechanism having a snap action to effect a quick break of the circuit and preferably also a quick make.

The operating member is shown at 30 and it is 150 of the shaft 13.

. action when the spring passes the center and the preferably pivotally movable about an axis separated from the pivotal axis of the actuating member. The operating member is pivotally mounted on the before-mentioned stud 11, which connects the two plates 9, 9 of the bracket 8. Connected with the operating member 30 is a handle 31, and pivotal movement is limited by means of a transverse stud 32 which extends through a slot 32 in the said member 30. Preferably the operating member 30 is formed with a yoke 33 which embraces or bridges the shaft 13 of the actuating member. In other words, the operating member 30 is provided with a relatively large opening 34 through which the shaft 13 extends.

The operating member is operatively connected with the shaft 13 by means of a tension coil spring 35 which in theparticular construction disclosed constitutes an essential part of the quick-makeand-break mechanism. The spring is connected at one end with the central portion of the yoke 33 and at the other end with the crank portion 13 Fig. 6 shows the operating and actuating members in the positions corresponding to the closed-circuit positions of the contact members. The tension spring 35 tends to hold the parts in the position shown. It will be apparent, however, that when the operating member is moved to the position shown in Fig. 'lthe inner or right hand end of the spring 35 is moved downward over the center of the shaft 13, with the result that the actuating member and the connected contact members are moved by the spring, to the position shown in Fig. 7. This movement takes place quickly and with a snap contacts are, therefore. quickly separated. It will similarly be apparent that when the operating member is moved from the position shown in Fig. '7 to the position shown in Fig. 6 the inner or right hand end of the spring 35 is moved upward over the center of the shaft 13, with the result that the actuating member with the connected contact members is moved to the closed position with a quick or snap action.

In order to minimize arcing when the movable contacts 18 and 19 are separated from the stationary contacts 2 and 3, I preferably provide a construction embodying the invention set forth in my Patent No. 1,947,276 dated February 13,

- 1934 for Electric circuit controlling apparatus.

vAs illustrated there are two series of metallic pieces 36, 36 which are mounted on the respective side plates 15, 15 of the contact member. These metallic pieces are spaced apart and are so arranged as to pass in close proximity to the corresponding stationary contact 2 or 3 when the contact member moves in the circuit opening direction. These conducting metallic pieces 36, -36 act'upon any are that may be formed so as to break it up into smaller arcs, the result being that with the voltage for which the circuit breaker is designed the several smaller-arcs in series cannot be maintained and are therefore automatically extinguished.

Preferably each circuit breaker mechanism is enclosed in its own individual casing or cover. Covers 37, 3'7 are shown, these being connected with the main base 1 by means of screws 38', 38. Preferably each cover 3'7 is provided with slots 39, 39 adjacent the contacts so as to permit arc formed gases, if any, to freely escape. These covers have the primary function of protecting the enclosed mechanisms, excluding dirt and preventing unauthorized tampering or adjustment When the circuit breaker is intended to be used for a three wire circuit, additional wire terminals 40 and 41 may be provided for the attachment of wires forming the third or neutral leg of the circuit.

It may be desirable not only to separately enclose each circuit breaker mechanism as has been described, but also to enclose the entire circuit breaker. I have shown the circuit breaker enclosed in a metallic box-or casing 42 having an openable front cover 43. The base 1 is connected to the rear wall of the cabinet by means of screws 44, 44. The cover 43 has a slot therein for the handle 31, the said slot being of sufiicient length to permit the necessary movements of the handle. Preferably the handle 31 is provided with arcuate extensions 31 31 which move in close proximity with the cover 43 and prevent unauthorized access to the interior of the casing through the slot.

The circuit breaker shown in Figs. 9 to 14 is similar in principle to that shown in Figs. 1 to 8 but it differs considerably as concerns details of construction. The circuit breaker as shown in Figs. 9 to 14 is adapted to be used as a pendant switch for controlling a circuit such as that for a light or a fan; but it will be understood that the invention is by no means limited to a circuit breaker used for this particular purpose.

As shown, the housing for the circuit breaker comprises two main parts 45 and 46 which may be formed of a molded insulating material. The part 45 constitutes the bottom and two sides of the housing, and the part 46 constitutes the top and the remaining two sides of the housing. The part 46 has a cord receiving aperture at 46 as shown. The two parts45 and 46 may be connected together by means of screws 47, 4.7. The circuit breaker proper is entirely mounted on the housing part 45 and the housing part 46 may be removed without in any way interfering with the mechanical functioning of the circuit breaker parts.

Extending from side to side of the housing member 45 are two supporting members or plates 48, 48 which are held in place by means of screws 49, 49. Electrically connected with the two plates 48, 48 are stationary electric contacts 50, 50 which are preferably held in place by two of the screws 49, 49 alr ady referred to. Carried by the plates 48, 48 are screws 51, 51 which constitute wire terminals. It will be obvious that wires engaged by the screws 51, 51 will be-in electrical connection respectively with the two stationary contacts 50, 50.

As shown most clearly in Fig. 14 each of the plates 48 has an offset extension 48 to which is riveted a transversely extending stud 52. Each stud 52 has at its inner end two portions 52 and 52 which are reduced in diameter and which serve as pivotal supports for the contact member and actuator respectively.

The contact member comprises two spaced side plates 53, 53 which are provided with' hearing apertures 53 53 through which the reduced end portions 52 52 of the respective studs 52, 52 project. The two plates'53, 53 are held in spaced relationship in part by a spacing bar 54 and in part by other means to be presently described. The contact member is biased for movement in the circuit opening direction, that is, in the clockwise direction as viewed in Figs. 10, 11 and 12 by means of a coil spring 55 surrounding one of the studs 52. One end of the spring engages the corresponding side plate 53 of the contact a Looaese member and the other end of the spring engages that with the parts in the position shownin Fig. the corresponding plate 48. Movement of the 10 the passage of excess current through the contact member in the clockwise direction under thermal strip will cause it to deflect toward the the influence of the spring 55 is limited by the right, thus releasing itself from the actuator 61 side wall of the housing as clearly shown in and permitting the contact member to automati- Figs. 11 and 12. cally move in the clockwise direction to the open- Two laterally projecting movable contacts 56, circuit position shown in Fig. 12. This action 56 are carried by the contact member-at the sides takes place irrespective of the actuator 61 and thereof, these contacts projecting laterally from it is thus apparent that operation of the circuit the respective side plates 53, 53 and being adaptbreaker cannot be prevented merely by holding ed to be engaged with and disengaged from the the handle 62 in its closed-circuit position. After respective stationary contacts 50, 50. The said the circuit has been automatically opened it is contacts 56, 56 are in the form of metallic plates necessary to then move the handle 62 to the openwhich project inward through slots 53*, 53 in circuit position, as shown in Fig. 11, in order to the respective side plates 53, 53. Each contact permit reengagement of the thermal strip with 56 is provided with opposite notches at 56 and the actuator. After that the circuit breaker can the narrower notched portion of the contact be operated as a switch in the usual way as alfits the narrower portion of the corresponding l y'd slot 53*. Extending transversely between the Movement of the actuator and contact member two side plates is an insulating bar 57, the ends in the counterclockwise or circuit-closing direcof which project into the wider portions of the t on is Ordinarily limited y the engagement of slots 53*, 53*, so as to hold the contacts in place. the movable contacts 56 with the stationary con- The inner ends of the contacts engage the bar tacts 50, 50, but there is also provided atransverse 5'7 at the right hand side thereof as i d i insulating bar 65 which extends transversely be- Fig. 14-and are held in place by means of screws tw the W plates The plates 53 58, 5s. The contacts are provided with integ'al a provided w notches 53. 53 w h n ma extensions 56*, 56 and a bi-metallic strip 59 lS\. y provide Clearance for the bar 65 as C y connected to these extensions by means of screws ShOWn in 0- It W be Observed that the 60, 60. The function of the bi-metallic strip 59 bar 65 is not normally engaged y either t is similar to that of thestrip 27 and repetition teet member the actuator but that i does of the description is unnecessary. I serve as a stop for the actuator upon automatic On the reduced portions 52 52 of the st d release of the contact member as shown in Fig. 52, 52 there are carried bushings 52, 52, and on these bushings there is pivotally mounted an What I claim is! actuator 61. The end portion 61 of the actuator An automatic circuit breaker Comprising in is adapted to be engaged by the hooked portion Combination, a manually movable Operating 59 ofthe lei-metallic strip 59, wh th parts member, an actuating member movable indeare so engaged the contact member and the parts Pendently 0f the Operating member, a Contac carried thereby are mechanically connected with member movable independently of the Operating the actuator so as to be normall t ll d and actuating members and normally connected thereby. It will be observed that the actuator w h a in m m s as to be controlled and the contact member in their upper closed- I ing purposes.

61 is of U- shape and that the space between the thereby, a m ism p a v y n rp legs is entirely unobstructed, tween the operating and actuating members and The operating member or handle i shown as serving upon movement of the former to effect being slidably'-mounted instead of rotatably circuit-opening or circuit-closing movements of mounted as in the first described construction. t latter a d 0f the ta member, e a d The housing member 45 is provided with a groove mechanism including a spring for efieeting the 45% which serves as a guideway for a handle op movement with a d p t snap member 62. This handle member 62 has an arm action, and an element inherently responsive to 63 projecting inward therefrom, the arm being abnormalcurrent conditions in the circuit and movable in a 'slot 45 in the said housing memconstituting at least a part of a mechanical conber 45. A tension coil spring 64 is connected benection between the said actuating and contact tween the inner end of the arm 63 and the bridge members, the said element upon the attainment portion of the U-shaped actuator 61. The relaof an abnormal current condition in the circuit tionship of the parts is such that,when the handle being relative y movable by reason of its OWn member 62 is in its upper position as shown i inherent electro-responsive characteristics so as Fig. 10 the spring 64 lies above the pivotal axis to render the said mechanical connection ineffecof the actuator 61 and thus holds the actuator tiVe and to thereby permit the Contact e b to move to its open-circuit position independently circuit positions. When the handle member 62 of the actuating m m jis moved to its lower position as shown in Fig 2. {in automatic circuit breaker compris ng in 11 the spring 64 is carried below the pivotal axis combmatlon, a manually movable ,0per ating of the actuator 61 and the actuator and the conmember, an actuatmg member b tact member are moved to their lower open-cirtly of the operating member, a movable t, positions t 111 apparent t on contact member biased independently of the actucount of the over-the-center action of the-spring ating member tOWeI'd its Open-Circuit pos o the actuator and contact member will be moved and releesebly eonneetible W t the tuat n quickly and with a snap action to their closedmem er so s to be n m y rolled h r y, circuit positions or to their open-circuit positions a qu C mechanism p v y as the case may be. The circuit breaker can thus p ed between the Operating and actuating be operated by the handle 62 for normal switchmembers and serving upon movement of the former to effect quick circuit-opening or circuit- The action of the thermal strip 59 is similar closing movements of the latter and of the conto that already described. It will be apparent tact member, and an element inherently responsive to abnormal current conditions in the circuit and constituting at least a part of a mechanical connection between the said actuating and contact members, the said element upon the attain-' ment of an abnormal current condition in the circuit being relatively movable by reason of its own inherent electro-responsive characteristics so as to render the said mechanical connection ineffective and to thereby permit the contact member to move to its open-circuit position independently of the actuating member.

3. An automatic circuit breaker comprising in combination, a manually movable operating member, an actuating member movable independently of the operating member, a contact member movable independently of the operating and actuating members and normally connected with the actuating member, a mechanism operatively in terposed between the operating and actuating members and serving upon movement of the former to effect circuit-opening or circuit-closingv movement of the latter and of the contact member, the said mechanism including a spring for effecting the opening movement with an independent snap action, and a thermostatic bi-metallic latch normally movable with the actuating and contact members and normally operative for mechanically connecting them, the said latch being arranged to beheated upon the attainment of an abnormal current condition in the circuit and to be thus deflected so as to mechanically release the contact member and permit it to automatically move to open-circuit position.

4. An automatic circuit breaker comprising in combination, a manually movable operating member, an actuating member movable independently of the operating member, a contact member movable independently of the operating and actuating members and normally connected with the actuating member, a mechanism operatively interposed between the operating and actuating members and serving upon movement of the former to effect circuit-opening or circuit-closing movement of the latter and of the contact member, the said mechanism including a spring for effecting the opening movement with an independent snap action, and a thermostatic bi-metallic latch normally movable with the actuating and contact members and normally operative for mechanically connecting them, the said latch being connected in the circuit so as to be'automatioally deflected upon-the attainment of an abnormal current condition and to be thus deflected so as to release the contact member and permit it to automatically move to open-circuit position.

5. An automatic circuit breaker comprising in combination, a manually movableoperating member, an actuating member movable independently of the operating member, a contact member movable independently of the operating and actuating members and normally connected with the actuating member, a mechanism operatively interposed between the operating and actuating members and serving upon movement of the former to effect circuit-opening or circuit-closing movement of the latter and of the contact member, the said mechanism including a spring for effecting the opening movement with an inde pendent snap action, and a thermostatic bi-metallic strip directly connected with and carried by the contact member and serving in and of itself as a releasable latch normally operative for mechanically connecting. the actuating and contact members, the said latch being connected in upon the attainment of an abnormal current condition andto thus mechanically disconnect the contact member from the actuating member and permit the said contact member to automatically move to its open-circuit position.

6. An automatic circuit breaker comprising in combination, a manually movable pivoted operating member, an actuating member pivoted for independent movement about an axis separated from that of the operating member, a contact member movable independently of the operating and actuating members and normally connected with the actuating member so as to be controlled thereby, a mechanism operatively interposed between the operating and actuating members and serving upon movement of the former to eifect circuit-opening or circuit-closing movements of the latter and of the contact member, the said mechanism including a spring for effecting the opening movement with an independent snap action, and an element inherently responsive to abnormal current conditions in the circuit and constituting at least a part of a mechanical connection between the said actuating and contact members, the said element upon the attainment of an abnormal current condition in the circuit being relatively movable by reason of its own inherent electro-responsive characteristics so as to render the said mechanical connection ineffective and to thereby permit the contact member to move to its open-circuit position independently of the actuating member.

7. An automatic circuit breaker comprising in combination, a cranked actuating shaft. a manually movable operating member pivoted separately from the shaft and including a yoke which bridges the cranked portion of the shaft, a movable contact member biased independently of the actuating shaft toward its open-circuit position and releasably connectible' with the actuating shaft so as to be normally controlled thereby, a spring connected at one end to the said cranked portion of the shaft and at the other end to the said yoke at the center thereof, the said spring serving upon movement of the yoke to effect quick circuit-opening or circuit-closing movements of the actuating shaft and of the contact member, and an electro-responsive means serving upon the attainment of abnormal current conditions in the circuit to release the contact member from the actuating member for independent automatic circuit-opening movement;

8. An automatic circuit breaker comprising in combination, a manually movable operating member, an actuating member movable inde-, pendently of the operating member, two movable contact members each biased independently of the other and independently of the actuating member toward its open-circuit position and each releasably connectible with the actuating memher so as to be normally controlled thereby, a mechanism operatively interposedbetween the operating and actuating members and serving upon movement of the former to effect circuitopening or circuit-closing movements of the latter and of the contact members, the said mechanism including a spring for effecting the opening movement with an independent snap action, and two electro-responsive means each serving upon the attainment of abnormal current conditions in the circuit to release the corresponding contact member from the actuating member for independent automatic circuit-opening movement.

9. An automatic circuit breaker as set forth in claim 8, wherein the actuating member and the two contact members are pivotally movable about a common axis.

10. An automatic circuit breaker as set forth in claim 8, wherein the actuating member and the two contact members are pivotally movable about a common axis, and wherein the operating member is pivotally movable about an axis separated from the first said axis.

11. An automatic circuit breaker as set forth in claim 8, wherein. the actuating member comprises a pivotally movable shaft on which the contact members are pivotally supported and having a cranked portion between the contact members, and wherein there is an over-the-center spring connected with the said cranked portion of the shaft.

12. An automatic circuit breaker comprising vin combination, a movable actuator, a contact member biased for opening movement independently of the actuator, a stationary electric contact, a movable electric contact on the contact member engageable with the stationary contact, an electro-responsively controlled mechanical connection between the actuator and the contact member normally enabling the former to move the latter to engage and disengage the said contacts, the said mechanical connection being automatically releasable upon the attainment of abnormal current conditions to permit automatic opening movement of the contact member, and a series of spaced conducting pieces on the contact member adjacent the movable contact and movable in a path adjacent the stationary contact.

13. An automatic circuit breaker asset forth in claim 12, wherein the actuator and the contact member are movable pivotally about a common axis.

14. An automatic circuit breaker comprising in combination, a pivotally movable actuator, a contact member pivoted coaxially with the actuator and biased for opening movement independently thereof, two stationary electric contacts at the respective sides of the contact member, two movable electric contacts on the contact member at the sides thereof engageable respectively with the stationary contacts, anelectro-responsively controlled mechanical connection between the actuator and the contact member normally enabling the former to move the latter to engage and disengage the said contacts, the said mechanical connection being automatically releasable upon the attainment of abnormal current conditions to permit automatic opening-movement of the contact member, and two series of spaced conducting pieces'on the contact member adjacent the respective movable contacts and movablein paths adjacent the respective stationary contacts.

15., An automatic circuit breaker as set forth in claim 14, wherein the contact member includes two parallel spaced side plates of conducting material and wherein the conducting pieces of the 'two series are carried by and project transversely from the respective side plates.

16. An automatic circuit breaker comprising in combination, an'operating member guided for reeaeee snap action, and an electro-responsive means serving upon the attainment of abnormal current conditions in the circuit to release the contact member from the actuating member for inde-. pendent automatic circuit-opening movement.

.17. An automatic circuit breaker as set forth in claim 16, wherein the mechanism interposed between the operating member and the actuating member includes an over-the-center spring for effecting quick circuit-opening and circuit-closing movements.

18. An automatic circuit breaker as set forth in claim 16, wherein the actuating and contact members are enclosed in a casing having a slot therein, and wherein the operating member is supported on the casing for rectilinear movement adjacent theslot and has a manually engageable portion on the exterior of the casing and another portion extending inward through the slot and connected with the spring.

19. An automatic circuit breaker comprising in combination, two spaced supporting members, two studs carried by the respective supporting members and extending inward therefrom, a manually operable actuator pivotally mounted on the studs at the inner ends thereof, a contact member comprising two spaced side plates at opposite sides of the actuator and also pivotally mounted on the said studs, the said contact member being biased foropening movement independently of the actuator, two stationary electric contacts at the respective sides of thecontact member, two movable electric contacts on the contact member at the sides thereof engageable respectively with the stationary contacts, and an electro-responsively controlled mechanical connec tion between the actuator and the contact member normallyenabling the former to move the latter to-engage and disengage the said contacts, the said mechanical connection being automatically releasable upon the attainment of abnormal current conditions to permit automatic opening movement of the contact member.

20. An automatic circuit breaker as set forth in claim 19,-wherein the actuator is U-shaped, wherein there is an operating member manually movable independently of the actuator, and wherein there is an over-the-center spring connecting the operating member with the bridge portion of the actuating member, the said spring upon movement of the operating member being Lnovable between the legs of the actuating mem- JOSEPH SACHS. 

